The algorithm.

and a judgement
about how many accesses the provider can sustain per time.

These things are entered into a searchable database.

All participants can search and browse the descriptions of all available
resources. They can see
the description and the access state - how many accesses are happening
per time, how many are left; what they don't see is the URL.

If they like the descriptions, they buy accesses to the actual documents
with play money, tokens. Half of the tokens is "paid" to
the person who entered the URL; half of it is deducted by the
server maintainers to keep the system hungry.

URLs are sold only as many times as they can sustain accesses.
If the URLs don't work, the buyers can complain back to the system
and get their money back (if necessary, from the initial provider's
account); the URL is removed from circulation.

Earning tokens.

If you enter a resource that others access, you earn tokens to access
the resources that others entered. The more
popular your resource is, the faster you get your tokens.

If you run out of tokens, you can generate new ones
by mirroring existing resources that are in high demand; you buy a
one-time peek at something and use that peek to copy it, then
sell accesses to the copy.

Since the accesses are counted, you can safely remove the copy after
it has been accessed by the people you sold it to.

Scaling

When market accesses themselves become a bottleneck, their own accesses
might become commodities that are sold and bought.